System for electroplating a strip

ABSTRACT

A system for continuously electroplating a portion of a strip includes an unwinding reel station from which the non-electroplated strip is unwound, a first electroplating station, a driven winding reel station in which the electroplated strip is wound on a reel, and a control unit. The first electroplating station includes:
         a circular horizontally disposed support means at which outer edge the strip is held, the area to be plated protruding downward,   an endless drive belt abutting a part of the circumference at the outer edge, the strip being held between the outer edge and the drive belt and conveyed in the circumferential direction,   a drive for rotating the support means,   electroplating baths distributed over part of the circumference of the support means and arranged below the support means so that the region to be plated of the strip is conveyed through the baths and electroplated there.

The invention relates to a system for continuous electroplating at leasta portion of a strip, the system having an unwinding reel station fromwhich the non-electroplated strip is unwound and the strip is suppliedto a first electroplating station, the system having a driven windingreel station in which the electroplated strip is wound on a reel, andhaving a control unit.

BACKGROUND OF THE INVENTION

Known systems that operate continuously for electroplating a strip havea linear structure, i.e. systems in which the strip is conveyedcontinuosly and in which the portion of the strip which is suspendedfreely during the conveyance is electroplated. In an unwinding reelstation of the system the strip is unwound and then conveyed by asuitable conveyor system in a straight line through the electroplatingbaths and finally wound up in a winding reel station (“reel-to-reel”).Normally, the winding reel station is powered by a drive such that thefeed of the strip is caused by pulling the strip. A disadvantage of suchsystems is the great length, which necessitates correspondingly largeproduction halls. Another disadvantage is that the strip is guided onlyhere and there and the guidance is therefore unclean, rendering a veryprecise and localized electroplating difficult. The individualelectroplating baths in a linear arrangement are poorly replacable.Since the feed is carried out only through the winding reel station thewaste material is very large, namely at least one full length of theentire linear system. This makes the electroplating expansiveparticularly of stripes with short overall lengths.

EP 070 694 A1 discloses an electroplating system for single workpieces.The individual workpieces are clamped between a wheel and an endlessbelt lying against the outside of the wheel and conveyed throughelectroplating baths lying on the periphery. Such a system is indeedspace-saving, but strips cannot be electroplated. In addition, only afew and small electroplating baths can be used, since the periphery islimited. It is therefore suitable only for small workpieces that can beelectroplated with only a few electroplating baths.

In this application, the term electroplating bath is used generally forevery suitable bath that may be necessary for an electroplating process.These are pre-treatment baths, electrolytic cells and the like.

Starting from this prior art it is the object of the invention toprovide an improved electroplating system which is better suitable forelectroplating strips and with which the aforementioned disadvantagescan be avoided.

SUMMARY OF THE INVENTION

The system according to the inventive subject matter for continuouslyelectroplating a portion of a strip comprises an unwinding reel stationfrom which the non-electroplated strip is unwound and a firstelectroplating station and a driven winding reel station in which theelectroplated strip is wound up on a reel, and a control unit. The firstelectroplating station comprises:

-   -   a circular horizontally disposed support means that rotates        about a vertical axis and at which outer edge the strip is held,        wherein the area to be plated protrudes downward,    -   an endless drive belt which lies against a part of the        circumference at the outer edge, and the strip is held between        the outer edge and the drive belt and is conveyed in the        circumferential direction,    -   a drive for rotating said support means,    -   electroplating baths which are distributed over part of the        circumference of the support means and arranged below the        support means so that the region to be plated of the strip is        conveyed through the baths and electroplated there.

A main advantage of the inventive subject matter is its compactness,because the baths are no longer arranged in a long row, but are arrangedspace-optimized along the circumference of the circular support means. Atypical system according to the invention has a work space ofapproximately 9 m×9 m (about 30 feet×30 feet).

Another advantage is the low waste which is significantly smaller oreven completely eliminated, because if the strip is fed to the supportmeans and is clamped between the outer edge and the drive belt, it canbe conveyed through the electroplating baths over the full length.

Thereby a further advantage can be seen, namely that the strip is guidedalong its full length and is driven along the entire length of that partof the strip which is located above the baths, the strip is thus clampedat the support means. The drive belt fulfills two functions, namely adriving function and a holding function for holding the strip.

The electroplating baths arranged below the support means are easilyaccessible and can easily be replaced.

Because the strips to be electroplated are quite long andcorrespondingly heavy, the unwinding reel station is usually driven.Then, the driving speed of the electroplating station and the speed ofthe unwinding reel station should match exactly. This can either berealized by precision motors which can run exactly synchronously over along period of time. Such motors are correspondingly expensive. It canalso be achieved by an embodiment of the inventive subject matter inthat the drive of the unwinding reel station is adjusted with regard tospeed to the drive speed of the supporting means via a first speedmatching device.

In an embodiment, the first speed matching device comprises a rollerwhich is mounted movably to the side with regard to the conveyingdirection of the belt. The unwounded strip runs over the roller and theroller keeps the strip in tension and the displacement of the roller isdetected by the control unit and the control unit adjusts the drive tothe unwinding reel station. Then the drive of the unwinding reel stationcan be regulated so that the roller is kept to a desired displacement.

In a further embodiment of the invention, the first electroplatingstation comprises a pre-tensioned arranged feed roller for correctlyfeeding the strip between the outer edge of the support means and thedrive belt.

As explained above, the unwinding reel station comprises the first speedmatching device. For the same reason, the winding reel station comprisesa second speed matching device as well for matching the drive of thewinding reel station to the driving speed of the support means.

For special electroplating tasks five baths are often not enough. Theinventive system is easily extendable in that a second or even a thirdelectroplating station can easily be added. The second and all furtherelectroplating stations are identically constructed to the first one.The strip leaving the first electroplating station is fed to the secondand as the case may be to further electroplating stations.

For this, it is advantageously that the second electroplating stationcomprises a further speed matching device which is associated with afeed roller of the second electroplating station, and the feed roller ismounted pre-tensioned and movable to the side, so that a change of thedisplacement of the feed roller is a measure of a difference in speed ofthe drives of the two electroplating stations. This change is detectedand regulated by the control unit. In that way the drive speed of thesecond electroplating station is regulated in dependence of the speed ofthe first station.

It makes sense that the speed of each additional electroplating stationis matched to the speed of each predecessing station, respectively,namely the upward station. Altogether, the speed is controlled accordingto the driving speed of the first electroplating station.

A very small installation space is reached and an advantageousarrangement is realized if the electroplating baths of an electroplatingstation are arranged hexagon-like, forming five sides of a hexagon. Inthis arrangement the available space is used in an optimized way and theelectroplating baths can still be exchanged easily. The feed of thestrip to and from the station is done via the sixth side of the Hexagon.

For an easy exchange it is advantageously if each electroplating bathcomprises an electrical connection, and a code characterizing acorresponding electroplating bath can be transmitted to the control unitthrough the electrical connection. Then all the information about thebath is provided directly in the control unit and the bath can be drivendirectly with a specific program.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is explained by means of embodiments withreference to the drawings. In the drawings

FIG. 1 shows highly schematic representation of a system of theinventive subject matter in a top view;

FIG. 2 shows a view of an example of a strip to be electroplated;

FIG. 3 shows a perspective view of an electroplating bath of the systemaccording to the the inventive subject matter;

FIG. 4 shows a schematic representation as in FIG. 1 of an embodiment ofthe system.

DETAILED DESCRIPTION OF THE DRAWINGS

An inventive system 10 for continuously electroplating a strip 12comprises an unwinding reel station 14 from which reel thenon-electroplated strip 12 is unwound and supplied to a firstelectroplating station 16. The system 10 further comprises a drivenwinding reel station 18 in which the electroplated strip 12 is wound upon a reel and further comprises a control unit 20.

The unwinding reel station 14 comprises a supply reel 14-1 on which thestrip to be electroplated 12 is stored, a guiding roller 14-2 forcorrectly guiding the strip 12 and an unwinding drive 14-3.

The first electroplating station 16 includes a circular and horizontallyarranged support means 22. In the illustrated embodiment, the supportmeans 22 consists of a metal ring 24 which is held by support rollers26. The ring 24 can rotate in the horizontal plane about a verticalaxis. The ring 24 consists for example of stainless steel.

The ring 24 is driven by an endless drive belt 30. For this, the drivebelt 30 lies against the outer edge 28 of the ring 24 over a part of thecircumference and is fed back via guide rollers 32 and via a driveroller 34. The drive roller 34 is driven by a ring drive 35 so that thering 24 of the support means 22 rotates.

The strip 12 to be electroplated is shown in a side view in FIG. 2. Thestrip 12 may e.g. be a punched strip which comprises serial connectedparts 36, for example pins for plugs having one end 38 to beelectroplated and which will then be individualized by punching inanother later process. The strip 12 shall be electroplated at least inthe region which comprises the ends 38 of the parts 36. The strip 12 canbe hold at the other end portion 39.

The strip 12 is guided by the guiding roller 14-2 of unwinding reelstation 14, the roller 14-2 is mounted in a pre-tensioned manner. Thestrip 12 is then guided by another guiding roller 40 of theelectroplating station 16 between the outer edge 28 of the ring 24 andthe drive belt 30 so that it is held in a non-slip manner and carriedalong with the rotating ring 24. Thereby the strip 12 is insertedbetween the outer edge 28 and the drive belt 30 in such a way that it isgripped only with its upper region by the outer edge 28 and drive belt30. The region to be electroplated (ends 38) protrudes downwards.Electrical contact to the strip 12 is provided through the metal ring 24so that the strip can be electroplated. The ring 24 itself is contactedelectrically via sliding contacts.

Furthermore, the electroplating station 16 comprises severalelectroplating baths 42 which are distributed over part of thecircumference of the support means 22 and are arranged below the supportmeans 22. The term “electroplating bath 42” is used in this contextgenerally and describes every bath that may be necessary for anelectroplating process. These are pre-treatment baths, electrolic cellsand the like.

In the top view of the embodiment according to FIG. 1, these baths 42have a trapezoidal shape so that they build a hexagonal shape ifarranged in series wherein each bath 42 builds one side of the hexagon.In that configuration, the space below the support means 22 is optimallyutilized. Thus five electroplating baths 42 can be arranged in anelectroplating station 16. Through the remaining sixth side of thehexagon, which is kept free, the strip 12 is fed to and from theelectroplating station. Therefore, the strip 12 is continuously guidedthrough each of the five baths 42 and treated there accordingly.

FIG. 3 shows a perspective view of such an electroplating bath 42. In aknown way the bath 42 has a central basin 42-1 in which electrodes areprovided. The strip 12 is moved through the basin to becomeelectroplated. Further, the bath 42 comprises an overflow basin 42-2 forcollecting the electrolyte, a pump system 42-3 and an electricalconnection, not shown. If necessary, the bath 42 can include additionalcomponents such as heating means, rectifier, and the like. Allcomponents of an electroplating bath 42 are mounted on a frame 42-4 thatrests on wheels 42-5 and thus, forms a carriage. At least the basins42-1 and 42-2 can be adjusted in height in order to remove theelectroplating bath 42 from the electroplating station 16 after it hasbeen lowered. In this way, the baths 42 are easily replaceable. Aninventive electroplating system 10 can thus quickly and easily beadapted to different electroplating processes.

The strip 12 is fed out of the electroplating station 16 and fed intothe winding reel station 18 via a further guiding roller 44. The windingreel station 18 is similar constructed as the unwinding reel station 14and comprises a reel 18-1 on which the belt 12 is wound, a guidingroller 18-2 for the correct feeding of the strip 12 and a winding drive18-3.

If all three drives, unwinding drive 14-3, ring drive 35 and windingdrive 18-3 rotate exact synchronously the belt is conveyed cleanly andwithout tension and without sagging. This is ensured by controlling thedrives via the control unit 20.

For synchronization between the unwinding reel station 14 and theelectroplating station 16 a first speed matching device is provided.This functions as follows. The guiding roller 14-2 is movably mounted,namely displaceable to the side and pre-tensioned mounted, which isindicated by the double arrow 50. The displacement of the guiding roller14-2 or an arm on which the guiding roller 14-2 may be mounted isdetected by the control unit 20. This is represented by a connectingline in FIG. 1. Depending upon the degree of displacement the controlunit 20 regulates the unwinding drive 14-3, so that the displacementalways corresponds to a desired displacement. The unwinding drive 14-3is thus regulated to the speed of the ring drive 35. The ring drive setsthe conveying speed. Then, the strip 12 has always the same and correcttension.

In an analogous manner, the winding drive 18-3 is controlled by thecontrol unit 20 using a second speed matching device using the guidingroller 18-2 which displacement (to a side) is also detected.

The control unit 20 is accommodated in a control cabinet, all parameterssuch as temperatures, speeds, and currents are displayed at a touchpanel and can be displayed and changed. The rectifier of all cellsprovide provide electric power (current and voltage). The line speed ofthe system is continuosly adjustable from 0 up to a maximum speed.

FIG. 4 shows a further embodiment of the system according to theinvention. For certain electroplating tasks the five baths 42 of thefirst 16 electroplating station are probably not enough. In this case,the system can be enlarged in a simple way in that anotherelectroplating station 16-2 is inserted between the first electroplatingstation 16 and the winding reel station 18. The second electroplatingstation 16-2 is constructed identically to the first one.

The strip 12 is supplied to the guiding roller 40-2 of the secondstation 16-2 after leaving the first station 16 (after the guidingroller 44). As in the first station, the strip is guided and transportedby means of the ring 24-2 through the electroplating baths 42-2 of thesecond station 16-2 and finally fed to the winding reel station 18 viathe guiding roller 44-2 and the strip 12 is wound there.

The synchronisation of the drives is a more complex problem now.However, the invention has the principle that the speed of the ringdrive 35 of the first station 16 is the one which sets the overallspeed. The control unit 20 takes over the complete control. The controlover the first speed matching device between unwinding reel station 14and first electroplating station 16 remains unchanged. The control ofthe ring drive 35-2 of the second electroplating station 16-2 isaccomplished such that the displacement (double arrow 60) of the guidingroller 40-2 which is also displaceable mounted is detected and fed as acontrol variable to the control unit 20, so that the ring drive 35-2 iscontrolled in such a way that a desired displacement of the guidingroller 40-2 is achieved. Finally, the control between the secondelectroplating station 16-2 and the winding reel station 18 is carriedout in the same way as the control between the first electroplatingstation 16 and the winding reel station 18 in the first embodimentaccording to FIG. 1.

Depending on requirements, the system 10 can be extended by a third oreven more electroplating stations in the same way. It makes sense tocontrol the drive speed of any further electroplating station accordingto the speed of each upstream station. Then overall, the drive speed isdetermined by the first station.

A further electroplating station can be useful if the strip 12 shall beelectroplated not only in some areas (at the ends 38) but shall beelectroplated completely. Then in the first electroplating station 16,the end portion 38 is electroplated and the strip 12 is gripped in theregion 39. Between the first and second electroplating station the strip12 is turned, i.e. twisted by 180°, so that it is inserted in to thesecond electroplating station upside down and is gripped there by thealready electroplated end regions 38. The region 39 which has not beenelectroplated in the first electroplating station 16 protrudes nowdownwards and can be electroplated in the second electroplating station16-2.

A coding which characterises a respective electroplating bath can betransmitted to the control unit 20 through the electrical connection inorder to simplify an exchange of an electroplating bath 42 or 42-2. Thenall information concerning the bath which was exchanged are directlypresent at the control unit 20.

What is claimed is:
 1. System (10) for continuously electroplating a portion of a strip (12) having an unwinding reel station (14) from which the non-electroplated strip (12) is unwound and having a first electroplating station (16) and having a driven winding reel station (18), in which the electroplated strip (12) is wound up on a reel, and having a control unit (20), wherein the first electroplating station (16) comprises: a circular horizontally disposed support means (22) that rotates about a vertical axis and at which outer edge (28) the strip (12) is held, wherein the area to be plated (38) protrudes downward, an endless drive belt (30) which lies against a part of the circumference at the outer edge (28) and the strip (12) is held between the outer edge (28) and the drive belt (30) and is conveyed in the circumferential direction, a drive (35) for rotating said support means (22), electroplating baths (42), which are distributed over part of the circumference of the support means (22) and arranged below the support means (22) so that the region (38) to be plated of the strip (12) is conveyed through the baths (42) and electroplated there.
 2. System according to claim 1, characterized in that the unwinding reel station is driven and the drive of the unwinding reel station is adjusted and the speed of the drive is matched to the drive speed of the supporting means via a first speed matching device.
 3. System according to claim 2, characterized in that the first speed matching device has a roller which is mounted movably to the side with regard to the conveying direction of the belt, the unwounded strip runs over the roller and the roller keeps the strip in tension and the displacement of the roller is detected by the control unit and the control unit adjusts the speed of the drive of the unwinding reel station in that the drive of the unwinding reel station is regulated to a desired displacement of the roller.
 4. System according to claim 1, characterized in that the first electroplating station comprises a pre-tensioned arranged feed roller for correctly feeding the strip between the outer edge of the supporting means and the drive belt.
 5. System according to claim 1, characterized in that the winding reel station has a second speed matching device for matching the speed of the drive of the winding reel station to the driving speed of the supporting means.
 6. System according to claim 1, characterized in that there is at least a second electroplating station to which the strip leaving the first electroplating station is fed.
 7. System according to claim 6, characterized in that the second electroplating station comprises a further speed matching device which is associated with a feed roller of the second electroplating station, and the feed roller is mounted pre-tensioned and movable to the side, so that a change of the displacement of the feed roller is a measure of a difference in speed of the drives of the two electroplating stations, said change is detected and regulated by the control unit.
 8. System according to claim 7, characterized in that the control unit adjusts all the drives to be controlled according to the drive of the first electroplating station.
 9. System according to claim 6, characterized in that a third electroplating station is provided.
 10. System according to claim 1, characterized in that the electroplating baths of the electroplating station are arranged hexagon-like, forming five sides of a hexagon, and the feed of the strip to and from the station is done via the sixth side.
 11. System according to claim 1, characterized in that each electroplating bath comprises an electrical connection and in that a code characterizing a corresponding electroplating bath can be transmitted to the control unit through the electrical connection.
 12. System according to claim 1, characterized in that the electroplating baths and/or the unwinding reel station and/or the winding reel station rest on wheels. 